1. Field of the Invention
This invention relates to the production of at least partially metallic articles, and in particular to the production of such articles with defined heat transfer channels.
2. State of the Art
Articles such as dies, moulds and other tools are typically required to operate within a specific temperature range in order to ensure that the operation for which they were designed proceeds smoothly and produces an optimised product. Examples of this are plastic injection moulding (PIM) techniques where it may be desirable to hold the dies at a temperature of, for example, 100.degree. C. As a further example, in the case of high pressure die casting (HPDC) techniques using aluminium alloys, a preferred temperature range may be 200.degree.-250.degree. C.
In both examples the injected material is at a higher temperature than the mould or die. The mould or die cools the injected material until it becomes substantially solid after which the product is ejected. In the process of cooling the injected material the mould or die becomes relatively hotter and must then be allowed to cool (or be artificially cooled) to return to the required operational temperature range.
To reduce cycle times, and therefore increase production efficiency, it is preferable to cool mould or dies during or after use by means of in-built heat transfer channels for cooling water to circulate within the mould or die. Typically, cooling channels such as these are made by drilling into the mould or die block during manufacture and fitting connections for the circulation of cooling water or, in some cases, cooling air. The construction of such cooling channels involves complex, accurate and expensive drilling and plugging of many channels.
In other embodiments it is envisaged that it may be desirable to transfer heat to the article, in which case heating fluid may be passed through the heat transfer channels.